In recent years, a decrease in size and weight, an increase in power output, and an increase in efficiency have been needed in a permanent magnet motor used in a hybrid car, a hard disk drive, and so forth. To realize such a decrease in size and weight, an increase in power output, and an increase in efficiency in the permanent magnet motor mentioned above, film-thinning and a further improvement in magnetic properties have been needed for a permanent magnet to be embedded in the motor.
As to a method for manufacturing a permanent magnet to be used in a permanent magnet motor, a powder sintering method has been generally used. In this powder sintering method, first, a raw material is milled by a jet mill or the like (dry-milling method) to produce magnet powder. Thereafter, the resulting magnet powder is put in a mold and pressed to mold to a desired shape. Then, the magnet powder molded to the desired shape in a solid state is sintered at a prescribed temperature (for example, at 1100° C. for the case of Nd—Fe—B-based magnet) for completion (See, for example, Japanese Laid-Open Patent Application Publication No. 2-266503). In addition, in order to improve magnetic properties of a permanent magnet, magnetic field orientation is generally carried out by applying a magnetic field from outside. In the method for manufacturing a permanent magnet by a conventional powder sintering method, magnet powder is filled into a mold at the time of press molding; and then, a pressure is applied after a magnet field is applied thereto to carry out the magnetic field orientation so as to mold the magnet powder to a shaped body of compressed powder. In other method for manufacturing a permanent magnet such as an extrusion molding method, an injection molding method, and a roll molding method, a magnet has been molded by applying a pressure under the atmosphere in which a magnetic field is applied. By so doing, a shaped body having direction of the axis of easy magnetization of each magnet particle constituting the permanent magnet aligned in a direction of an applied magnetic field can be formed.